The present invention relates to a drive unit for driving a recording disk such as an optical information storage disk.
Recording disk drive units include a turntable for placing a recording disk thereon, a motor for driving the turntable, and a radial feed unit for moving a pickup head radially across the recording disk. Information can be recorded on or retrieved from the recording disk through the pickup head by moving the latter radially across the recording head while rotating the recording disk. The conventional motor is of a cylindrical shape and disposed directly below the turntable. Where the radial feed unit comprises a linear motor, the yoke and permanent magnet of the unit have to be located outside of the motor. As a result, the yoke and permanent magnet of the linear motor should extend radially outwardly of the recording disk in order to enable the pickup head to move in a stroke necessary for recording and retrieving any desired information.
Therefore, the recording disk drive unit cannot be reduced to a size substantially equal to that of recording disks unless the portion of the drive unit which is positioned radially beyond the disk is eliminated.
The prior cylindrical motor is unitized as an independent construction, and hence the recording disk drive unit cannot be reduced in thickness since it is necessary to increase the height of the motor, if the outer motor profile should not be increased in the radial direction, in order to achieve a torque necessary for a higher rotating speed.